Peaking is not available in simple AF but does work in DMF. In this mode the camera performs AF & then disengages the focus mechanism to allow manual focus. Usually focus is generally correct without further action but does allow fine tuning if this is required. The camera however can get confused when the subject is low contrast & the background is of greater contrast & this is where DMF becomes particularly useful.

DMF may be needed in close-ups where a specific part of a subject is required to be sharp , in an example already given perhaps the eyes are the specific area for focus. When DMF is selected with magnification this kicks in as the focus ring is turned , usually it needs adjusting around the already selected focus point , watch as focus improves or falls off until focus is optimal.

DMF requires some practice in handling the camera without shake etc & also good eyesight particularly in low light but success gets better over time. Peaking colours are weaker when in the magnified mode on close-ups but sometimes small flashes of colour can be seen & as focus moves they appear & disappear & need to be concentrated on.